Atmospheric Remote Sensing: Instruments

The Tunable Optical Profiler for Aerosol and oZone lidar (TOPAZ) lidar was designed and built in 2006 at the NOAA Chemical Sciences Laboratory. TOPAZ incorporates state-of-the-art technologies to make it compact and lightweight as well as having low power consumption. These features have allowed for flexibility in its application to numerous air quality field studies, both airborne and ground-based. Its wavelength flexibility permits optimization for differing atmospheric conditions including interference from other atmospheric components and allows dual-DIAL operation – introduction to Differential Absorption Lidar (DIAL) techniques.

TOPAZ was originally configured and deployed on the NOAA Twin Otter aircraft to participate in air quality studies where it provided wide-area mapping of ozone and aerosol distributions and transport near urban sources. The first example of this application was the Texas Air Quality Study (TexAQS) 2006. As the lidar was flown over and around the Houston area collecting ozone and aerosol backscatter profiles from flight level to near ground level, it produced a three-dimensional picture of the distribution of ozone and aerosols in the study area. Additional information obtained from the lidar data included boundary height determination and ozone plume flux measurements.

After several years of airborne operation, TOPAZ was reconfigured for deployment in a box truck (and, more recently, a trailer) for ground-based operation. The addition of a two-axis (one automated) scanner permits data collection from a few meters above ground level (AGL) through 6-8 km AGL, dependent on atmospheric conditions. Recent examples of TOPAZ applications in this arrangement include the California Baseline Ozone Transport Study (CABOTS) 2016 and the Fires, Asian, and Stratospheric Transport - Las Vegas Ozone Study (FAST-LVOS) 2017 experiments.

TOPAZ is also part of the NASA Tropospheric Ozone Lidar Network (TOLNet) for ground-based profiling of tropospheric ozone. In addition to the occasional deployment to field experiments, TOPAZ makes routine measurements in support of TOLNET goals including satellite ozone measurement validation and creating a long-term ozone measurement record under varied atmospheric conditions on the Front Range of Colorado.